Schott Ag

Yoshio Okano

Ulrich Peuchert

Yvonne Menke

Steffen Reichel

Joseph S Hayden

Jochen Alkemper

Martin Letz

Jose Zimmer

Carsten Weinhold

Frank-Thomas Lentes

Wolfram Beier

Peter Blaum

Guenther Kron

A transparent, polycrystalline ceramic is described. The ceramic comprises crystallites of the formula ACBDEF, whereby A and C are selected from the group consisting of Li, Na, Be, Mg, Ca, Sr, Ba, Al, Ga, In, C, Si, Ge, Sn, Sc, Ti, Zn, Zr, Mo, Ru, Pd, Ag, Cd, Hf, W, Re, Os, Ir, Pt, Hgand mixtures thereof, B and D are selected from the group consisting of Li, Na, K, Mg, Al, Ga, In, Si, Ge, Sn, Sc, Ti, Zn, Y, Zr, Nb, Ru, Rh, La, Lu, Gdand mixtures thereof, E and F are selected mainly from the group consisting of the divalent anions of S, Se and O and mixtures thereof, x, u, y, v, z and w satisfy the following formulae0.125&#x3c;()/()&#x2266;0.55=4and at least 95% by weight of the crystallites display symmetric, cubic crystal structures of the spinel type, with the proviso that when A=C=Mgand B=D=Al, E and F cannot both be O.

Spinel optoceramics

The method for producing at least one rotationally symmetrical lens consisting of an opto-ceramic includes the step of moulding a ceramic green body for the lens, wherein the mould has a shaping surface, which is described by the following equation B: ygives a position on an optical axis; x designates a perpendicular distance from the optical axis to the surface; k, c, and a, a, a, a, . . . are constants describing a surface of the lens to be moulded and z=|x|+b, wherein b is a constant with a value greater than 0 and less than 0.3 mm, which is a measure of a deviation of the shaping surface from the surface of the lens.

Method for producing a rotationally symmetric lens from a ceramic green body and moulding tool for performing the method

The moulding tool is a near-net-shape negative mould for shaping a ceramic green body for the lens. The mould has a shaping surface, which is described by the following equation B: y1 gives a position on an optical axis; x designates a perpendicular distance from the optical axis to the surface; k, c, and a, a, a, a, . . . are constants describing a surface of the lens to be moulded and z=|x|+b, wherein b is a constant with a value greater than 0 and less than 0.3 mm, which is a measure of a deviation of the shaping surface from the surface of the lens.

Moulding tool for moulding a ceramic green body and use of said moulding tool

The refractive, transmissive or diffractive optical elements are made from a ceramic containing one or more oxides of the type XO, which is transmissive for visible light and/or for infrared radiation and which has a cubic crystal structure analogous to that of YO. In preferred embodiments X is Y, Sc, In, or a lanthanide element, namely La to Lu, and in particular is Lu, Yb, Gd, or La. Also mixtures of oxides of the type XOwith oxides having different stoichiometries, such as HfOand/or ZrO, may be present, as long as the cubic structure of the ceramic is maintained.

Optical elements made from ceramics comprising one or more oxides of Y, Sc, in and/or lanthanide elements and mapping optics including the optical elements

The opto-ceramics and optical elements of the present invention are transmissive to visible light and/or to infrared radiation. They consist of a crystal combination in which individual crystallites have a cubic structure of the type YOand are made from InOor a mixture of oxides of the type XOin which X=Y, Lu, Sc, Yb, In, Gd, or La. Also mixtures of XOwith oxides having different stoichiometries, such as zirconium and hafnium oxide, are possible, as long as the cubic structure of the opto-ceramic is maintained. The optical elements prepared from the opto-ceramics are particularly suitable for mapping optics, such as objectives having reduced chromatic aberrations, in particular with approximately apochromatic mapping behavior. The optical elements of the present invention may be used in lens systems in combination with lenses of glass, but also with other ceramic lenses.

[object Object]

The optical elements are made from an opto-ceramic material that is characterized by high density, transparency for visible light and IR, high refractive index, high Abbe number and outstanding relative partial dispersion. Mixed oxides are sintered to obtain the opto-ceramic material. The mixed oxides contain zirconium oxide and hafnium oxide mixed with one or more oxides of yttrium, scandium, lanthanide elements, and optionally mixed with one or more of SiO, NaO, and TiO. Alternatively the mixed oxides contain zirconium oxide and hafnium oxide mixed with CaO and/or MgO and optionally mixed with one or more of SiO, NaO, and TiO. In addition, the mixed oxides can also include one or more oxides of Al, Ga, In, and Sc; optionally one or more oxides of yttrium, some lanthanide elements; and optionally one or more of SiO, NaO, MgO, CaO, and TiO.

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Mainz, Germany

Yoshio Okano